Virtual holonomic constraint approach for planar bipedal walking robots extended to double support

Scheint, Michael; Sobotka, Marion; Buss, Martin

doi:10.1109/cdc.2009.5400535

Cited by 13 publications

(9 citation statements)

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“…A non-trivial double-support period could be modeled using a compliant ground contact model, which has been done in the context of output linearization [34]. However, the constant-curvature property of the COP trajectory in shank coordinates does not hold after contralateral heel strike.…”

Section: Discussionmentioning

confidence: 99%

Towards Biomimetic Virtual Constraint Control of a Powered Prosthetic Leg

Gregg

Sensinger

2014

IEEE Trans. Contr. Syst. Technol.

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This brief presents a novel control strategy for a powered prosthetic ankle based on a biomimetic virtual constraint. We first derive a kinematic constraint for the “effective shape” of the human ankle-foot complex during locomotion. This shape characterizes ankle motion as a function of the Center of Pressure (COP)–the point on the foot sole where the resultant ground reaction force is imparted. Since the COP moves monotonically from heel to toe during steady walking, we adopt the COP as a mechanical representation of the gait cycle phase in an autonomous feedback controller. We show that our kinematic constraint can be enforced as a virtual constraint by an output linearizing controller that uses only feedback available to sensors onboard a prosthetic leg. Using simulations of a passive walking model with feet, we show that this novel controller exactly enforces the desired effective shape whereas a standard impedance (i.e., proportional-derivative) controller cannot. This work provides a single, biomimetic control law for the entire single-support period during robot-assisted locomotion.

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Section: Discussionmentioning

confidence: 99%

Towards Biomimetic Virtual Constraint Control of a Powered Prosthetic Leg

Gregg

Sensinger

2014

IEEE Trans. Contr. Syst. Technol.

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“…Note that the definition of cyclic variable in [18,19] is stated as [{∂D(q)}/∂q i ] = 0 and is weaker than (7). The latter implies in addition ∂V/∂q i = 0.…”

Section: Recalls On General Non-linear Systemsmentioning

confidence: 95%

Classification of two‐degree‐of‐freedom underactuated mechanical systems

Maalouf

Moog

Aoustin

et al. 2015

IET Control Theory & Applications

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International audienceA new classification for two-degree-of-freedom mechanical systems is introduced, based on structural controlproperties. The largest feedback linearisable subsystem with internal stability is considered for such systems. The classification is depending on the closed-loop system that can be achieved under the constraint of internal stability. It is shown that the generalised conjugate momenta corresponding to each degree of freedom play a crucial role for the considered mechanical systems

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“…In order to incorporate this constraint into optimization, the idea is, similar to the presented ones in [16], [17], to find a new set of minimal coordinates for the system under constraints and perform motion optimization in the new coordinates. The new coordinates w are chosen to contain the constrained variable p 4x and q 4 , the joint variable at the location of the spring.…”

Section: B Change Of Coordinates During Contact Phasementioning

confidence: 99%

Optimized parallel joint springs in dynamic motion: Comparison of simulation and experiment

Scheint

Sobotka

Buss

2010

2010 3rd IEEE RAS &Amp; EMBS International Conference on Biomedical Robotics and Biomechatronics

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Inspired by human tendon function, parallel springs in the joints of bipedal walking robots allow for a significant reduction of the cost of locomotion in simulation. An experimental setup is presented here which enables to verify the simulation results. The beneficial effects of parallel springs are investigated for a four-link robot arm equipped with a parallel spring at the last link. The desired motion results from simultaneous optimization of spring properties and motion which was shown to achieve the best reduction of actuation effort. Spring utilization is considered for two types of motion, free space motion and motion including contact with the environment at the end-effector. It is shown that the absolute reduction of effort through the utilization of an optimal spring is independent of friction. Hence, influence of the spring on effort is more relevant at higher speeds where the motion itself requires more actuation effort. Furthermore, for motion with environmental contact, a spring can reduce actuation effort more than in free space motion, especially for stiffer environments.

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Virtual holonomic constraint approach for planar bipedal walking robots extended to double support

Cited by 13 publications

References 13 publications

Towards Biomimetic Virtual Constraint Control of a Powered Prosthetic Leg

Towards Biomimetic Virtual Constraint Control of a Powered Prosthetic Leg

Classification of two‐degree‐of‐freedom underactuated mechanical systems

Optimized parallel joint springs in dynamic motion: Comparison of simulation and experiment

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